Retarding brake



Oct. 20, 1964 Filed Feb. 1, 1962 G. J. BURSAK 3,153,518

RETARDING BRAKE 3 Sheets-Sheet 1 INVENTOR GEORGE J.BURSAK BY /M/ ATTORNEY Oct. 20, 1964 G- J. BURSAK 3,153,518

RETARDING BRAKE Filed Feb. 1, 1962 3 Sheets-Sheet 2 nl l l l l l !!llllIIIIIIIII:I

INV ENTOR GEORGE J. BURSAK MM/KM 46 5+ ATTORNEY Oct. 20, 1964 G. J. BURSAK 3,153,518

RETARDING BRAKE Filed Feb. 1, 1962 3 Sheets-Sheet 3 INVENTOR GEORGE J. BURSAK AT TORN EY United States Patent 3,153,518 RETARDING BRAKE George J. Bur-salt, 5601 W. Auer Ave, Milwaukee, Wis. Filed Feb. 1, 1962, Ser. No. 17ti,47l 2 Claims. (Cl. 242-75.47)

This invention relates to torque generating apparatus suitable for use as applying controlled braking torque to supply rolls, and it more specifically resides in a rotatable shaft that is to be retarded, controllable braking mechanism having precise selective adjustment and a positive connection between a rotatable member of said braking mechanism and said rotatable shaft.

A mechanism for feeding flexible web material, such as paper, resinous films or the like, from a roll to a processing machine for printing or packaging, must present the web to that processing machine continuously, evenly, and properly aligned. The web must be fed at a constant rate of speed and a steady, predetermined, optimum tension must be maintained in the web. Usually the web material is pulled from its roll by the processing machine. Hence, the problem of controlling the feed of of the web to the processing machine becomes a prob lem of applying the proper braking force to the roll to prevent festooning and irregular feed on the one hand, and stretching or tearing of the web on the other hand.

In the past, common means for applying braking force to the roll of Web material consisted of a brake drum mounted coaxially with the roll and having a weighted leather strap swung over the drum to bear against its surface, retarding its rotation. That crude brake has proved less than adequate, particularly where more delicate, lightweight and deformable webs are used. Hence, the need was discerned for a braking device requiring a minimum experience to operate while permitting highly accurate control to compensate for the many and varying conditions effecting the operation of the brake. The operation of the brake may be changed, for example, by the consumption of the web stock, which reduces the leverage on the roll while increasing its rate of rotation; or, when the web material stretches under tension, reducing the effect of the brake; or, when dust or moisture in the atmosphere settles on the braking surfaces, reduc ing their coemcient afliictions; or, when the braking surfaces deteriorate under wear; or, when the thickness of the web varies. 7

It is an object of the present invention to provide a tension control unit which will allow smooth, constant speed feeding of a flexible web material to a processing mechanism.

It is another object of the present invention to provide a tension control unit capable of precise adjustment for the retarding force applied.

It is another object of the present invention to provide a tension control unit capable of maintaining a substantially constant retarding force.

It is another object of this invention to provide a tension control unit which will at all times accurately indicatethe comparative amount of retarding force being applied.

bodiments of the invention may be used and that structural changes may be made in the embodiment described without departing from the scope of the invention. Consequently, the following detailed description is not to be taken in a limiting sense; instead, the scope of the present invention is best defined by the appendant claims.

In the drawings:

FIG. 1 is a plan View with parts broken away and in section of a heat-sealing packaging machine illustrating the flexible web feeding portion of such machine together with a pair of tension control units embodying the present invention,

FIG. 2 is a front view in elevation of a tension control of FIG. 1 with portions cut away to illustrate parts of the circuitry used therein,

FIG. 3 is an end view in elevation of the control unit of FIG. 2 with portions cut away to illustrate the magnetic brake and milliammeter used therein,

It isanother object of this invention to provide a ten- FIG. 4 is a rear view in elevation of the control unit with portions cut away to illustrate the magnetic brake and some of the circuitry connected therewith, and to illustrate a form of positive connection between the mag netic brake and a flexible web mandrel, and

FIG. 5 is a wiring diagram of the circuitry used in the control tmit.

Referring to the drawings, FIG. 1 is a top View of a preferred embodiment of the invention operatively i11- stalled on a packaging machine, and although it is only incidental to the embodiment here, it might aid the visualization of the embodiment to note that the packaging machine is of the type that packages items, or substances, by heat sealing two films of heat scalable resin into pouches and depositing such items in the pouches as they are formed. Such heat scalable films are supplied in roll form and are hereafter referred to as webs, each web being indicated by the numeral 1. The two webs 1 are pulled inward toward each other from their respective rolls 2 and are fed first over guide rollers 3 and under guide rollers 4 from where they travel toward and over a pair of shafts 5. The webs 1 then pass downward between the shafts 5 into the pouch and filling portions of the machine; such portions are not shown here and are not important to the invention except that the pull on the webs is derived from such parts.

Each of the rolls 2 is fastened between two flanged collars 6 by means of screws 7 which are forced into paper mandrels 8 which form the cores of the rolls 2.

The flanged collars 6 are secured around quill shafts 9 by means of set screws 1b, which may be loosened to allow the flanged collars 6 to be adjusted on the quill' within one end of the quill shaft 9 so that its inner end is adjacent to the needle bearing 12 and its outer end bears against a thrust bearing 13, slidably mounted on.

the mandrel shaft 11. .The thrust bearing 13 abuts outwardly against adjusting nuts 15 and 16, which are threaded to engage the threaded surface of the mandrel shaft 11. At the other end of the quill shaft 9, a sleeve 19, similar to the sleeve 1%, is press fitted in position so that its inner end abuts the adjacent needle bearing 12, and its outer endabuts a thrust bearing 14. A coil spring.

2% is fitted around the mandrel shaft 11 and within the quill shaft 9 so that, its inner end bears against the thrust.

bearing 14 and its "outer end is anchored by appropriate- Patented Oct. 20,1964

means (not shown) to the mandrel shaft 11. Thus, the expansive force of the spring 20 is exerted against the thrust bearing 14 which bears against the sleeve 19, transmitting the spring force to the quill shaft 9. The quill shaft 9, in turn, transmits the force to the sleeve 18, which abuts the thrust bearing 13, which is secured against axial movement by the adjusting nuts and 16 engaging the mandrel shaft 11.

The quill shaft 9 is axially adjustable on its mandrel shaft 11 while the machine is in operation. By turning the adjusting nuts 15 and 16 clockwise, as viewed from the left hand side in FIG. 1, the thrust bearing 13 is forced inward against the sleeve 18. The inward movement and force of the adjusting nuts 15 and 16 is thus transmitted to the quill shaft 9, which in turn transmits the force to the sleeve 19, to force the thrust bearing 14 outward, compressing the spring 20. Similarly, by turning the adjusting nuts 15 and 16 counterclockwise, they move outward, and the compressed spring 20 is allowed to expand and force the quill shaft 9 and the thrustbearings 13 toward the adjusting nuts 15 and 16.

Pulleys, hereinafter referred to as spur pulleys 21, are tightly fastened around one end of each of the quill shafts 9 to rotate therewith. These spur pulleys are so named because, instead of having smooth friction surfaces, they have teeth 22 resembling in appearance and function those on a spur gear. The teeth 22 on the spur pulley 21 are seen most clearly in FIG. 4, which also most clearly shows a flexible drive belt 23, the inside surface of which is toothed correspondingly to the appointed spur pulley 21. The drive belt 23 passes around the spur pulley 21 on the quill shaft 9 and another spur pulley 24 on a magnetic brake 25, to form a positive drive connection therewith. The function of these pulleys and belts will be explained later.

Returning to FIG. 1, the ends of the mandrel shafts 11, which support the quill shafts 3 and associated elements described above, are supported in slots 26 in the ends of cantilever support members 27 which are fastened to'the machine frame 28. The lower cantilever support member 27 as it appears in FIG. 1, with its end slot 26 supporting the mandrel shaft 11 is best illustrated in FIG. 2. In FIGS. 2, 3 and 4 will be seen a precision controllable torque generating unit generally designated by numeral 29, which is mounted on a brake mounting arm 31) below the end of the quill shaft 9 which bears the spur pulley 21.

The brake mounting arm 30, as it appears in FIG. 2, is pivotally fastened to the cantilever support member 27 by a bolt 31, so that the torque generating unit 29 at the end of the brake mounting arm 30 may be raised or lowered. The position of the arm 34 and hence that of the torque generating unit 29, may be secured by means of a bolt 32 which extends from the side of the cantilever support member 27 through an arcuate slot 33 in the brake mounting arm 30, and which may be tightened to clamp the brake mounting beam 30 immovably against the cantilever support member 27. This pivotal mounting of the torque generating unit 29 allows it to be raised to loosen the drive belt 23. When the drive belt 23 is loosened, it may be removed from the spur pulley 21 on the quill shaft 9, allowing the entire mandrel shaft 11 to be removed. Thus, when the flexible web material 1 on one mandrel shaft 11 has been consumed by the machine, new material may be fed to the machine by removing the mandrel shaft 11 with the exhausted roll 2 and replacing it with another mandrel shaft 11 having a full roll 2 of material on it.

Turning now to the torque generating unit 29, FIG. 3 best illustrates its mounting on the brake mounting arm 39. That which has been generally referred to as a torque generating unit 29, consists of two main groups of components: (1) a magnetic brake 25 and (2) a control means contained in a control enclosure 37. As FIG. 3'

shows, the magnetic brake 25 is mounted in its housing .36 on the inside of the brake mounting arm 30, and a current indicating means 34, which in this embodiment is a milliammeter, and the variable control resistance 35 are mounted on the walls of the control enclosure 37 on the outside of the brake supporting arm 30.

The magnetic brake 25, as shown in FIG. 3, is readily available in commerce and is not applicants invention so it will not be described in detail here. It consists generally of an annular shaped rotatable brake member 38 rotatably mounted on a stationary brake shaft 39 adjacent an annular shaped stationary braking member 40 which has an annular cavity containing an electromagnetic coil winding 57 covered by an annular braking surface 41. The spur pulley 24 is attached to the rotatable brake member 38 to rotate therewith. The brake shaft 39 extends through the centers of the annular members mentioned and through a hole in the brake supporting arm 30 to which it is fastened by a nut 44.

The sheet metal housing 36 encloses the magnetic brake 25, and has an opening in the top to accommodate the drive belt 23. In addition, as appears in FIG. 4, the housing 36 has an opening with an associated clamp 47 to receive power input lines 46, and it has a fuse socket 48, which is associated with the power input lines46.

The control enclosure 37 is mounted on the opposite side of the brake mounting arm 30 from the magnetic brake housing as. The wall of the control enclosure 37 which is slanted upward will be denoted as the face 49 of the control enclosure 37, and it supports the current indicating meter 34 which has a dial 50 exposed for easy reading. The end wall 51 of the control box 37 supports the variable control resistance 35 with its control knob 52 mounted on the outside of the end wall 51. Finally, a full wave, bridge type rectifier 53 is mounted on the inside of the back wall 54 of the control enclosure 37. i

It will be noted that the brake mounting beam 30 is mounted on the outside of the cantilever support member 27, so that the spur pulley 24 which is fastened to the rotor 33 of the magnetic brake 25 is approximately underneath and aligned with the spur pulley 21 on the quill shaft 9.

Turning now to the circuit diagram in FIG. 5 showing the control device for the torque generating unit 29, terminals 55 are connected across an alternating current source through a fuse 48 to the input terminals of the full wave bridge rectifier 53. The terminals of the wire-wound variable control resistance 35 are connected across the output of the rectifier 53. One end of the winding 57 of the magnetic brake 25 is connected to one output terminal of the rectifier 53, and the other end of the winding 57 is connected to the sliding contact 58 of the variable control resistance 35 through the current indicating means 34. Thus, the variable control resistance 35 acts as a voltage divider and the current indicating means 34 indicates the amount of current passing through the branch of the circuit containing the magnet winding 57.

In operation, as installed in a packaging machine such as that shown in FIG. 1, the tension control unit of the invention solves the problems experienced with other tension control devices. The quill shaft 3 is caused to rotate on its needle bearings when the machine pulls the flexible web material 1 from the spools 2 which are held between the flanged collars 6. The spur pulleys 21, which are fastened tightly to the quill shafts 9, will, of course, rotate with the quill shafts 9 and transmit that rotation to the spur pulleys 24 on the rotors 38 of the magnetic brakes 25 by means of the drive belts 23.

Thus, the rotors 38 of the magnetic brakes 25 are caused to rotate with the quill shafts 9. It is important to the invention that the connection between the spur pulleys 21 and 24 be a positive drive connection as distinguished from a sliding friction connection. This positive drive connection maintains a constant correspondence between the rotation of the quill shaft 9 and the rotor 38, and thus a constant correspondence is maintained between the tension on the flexible web material 1 and the braking force of the magnetic brake 25.

The machine operator, desiring, for example, an increase of tension in the flexible web material 1, may turn the variable control resistance knob 52 so that the sliding contact 58 moves toward that terminal of the variable control resistance 35 which is connected to the pole of the rectifier output opposite from the pole to which one end of the magnet winding 57 is connected. By so doing, the amount of resistance in the branch of the circuit containing the magnet winding 57 is reduced, allowing more current to flow through the magnet winding 57. The larger the amount of current flowing through the winding 57, the greater is the magnetic flux generated, and the greater are the forces drawing the rotatable brake member 33 against the stationary braking surfaces 41 of the stationary braking member 49. As the rotatable brake member 38 and the stationary braking member 49 are drawn more tightly together, the friction between them increases, tending to retard the rate of rotation of the rotatable braking member 38, which tendency is transmitted via the spur pulleys 21 and 24, drive belt 23 and quill shaft 9 to the roll 2, where the tendency to retard rotation is translated into tension in the flexible web material 1.

It is desirable in the embodiment of the invention disclosed here to have the spur pulley 21 on the quill shaft 9 larger than the spur pulley 24 on the rotatable brake member 38. That differential allows a finer adjustment of the tension in the web material 1 because of the mechanical advantage given to the roll 2 as compared with the brake 25 requires a greater retarding force by the brake to effect the same force on the outside of the roll 2. More important here, however, is the increased speed given to the rotation of the rotatable brake member 38 as compared with the spool 2. In such a packaging machine, the spool 2 moves relatively slowly. The effect of the friction between the rotatable brake member 33 and the v spur pullleys 21 and 2d.

The drive belt connection betwen the magnetic brake 25 and the quill shaft 9 also allows easy removal of the mandrel shaft 11, and axial adjustment of the quill shaft 9. It is frequently desirable to remove the mandrel shaft 11 in order to put a new spool 2 of web material 1 on the quill shaft 9. The present invention allows rapid and easy removal of the shafts by simply pivoting the brake mounting beam 5% upward to loosen the drive belt 21, so it can be removed from the spur pulley 22. Also, to insure the proper alignment of the web material 1, the quill shaft 9 can be moved axially without affecting positive connection with the magnet brake 25.

In terms of the objects listed above for this invention it may now readily be perceived how they are accomplished. The friction brake surfaces 41 and 43 are enclosed in the housing 36 preventing foreign matter from being deposited between them. Thus, the retarding force of the brake 25 remains constant. The rheostat allows the operator to vary the braking force by such minute increments that the variation of the force in this environment may be considered as a continuum, as distinguished from changing increments. The milliammeter dial tells the operator, at any time, the comparative amount of force being applied to the brake, and it indicates the amount of change in force resulting from the rotation of the rheostat control knob. Thus, the machine may be efficiently operated by inexperienced personnel as well as experienced operators.

1 claim: 1. In a torque generating apparatus the combination comprising:

a shaft to be controlled; a first spur pulley mounted on said shaft for rotation therewith; a mounting arm movable toward and away from said spur pulley in a plane paralleling that of the pulley; a magnetic brake having a stationary braking member mounted by said arm, a brake shaft, a rotatable brake member on said shaft associated with said stationary members, and a second spur pulley of smaller diameter than said first spur pulley mounted on said brake shaft, said second spur pulley being aligned with said first spur pulley; a toothed belt linking said spur pulleys; a variable control resistance carried by said mounting arm; current indicating means carried by said mounting arm; rectifying means carried by said mounting arm; and circuit connections joining the resistance, rectifying means and current indicating means with one another and said magnetic brake to provide a variable control over said brake. 2. In a torque generating unit the combination comprising:

a pair of spaced cantilever members, each having a shaft mounting slot extending horizontally through its end;

a mandrel shaft, the ends of which are seated in said shaft mounting slots;

a quill shaft bearing-mounted to be freely rotatable around said mandrel shaft, axially adjustable on said mandrel shaft, adapted to receive a roll of flexible web material, and having a spur pulley fastened on one end; i

a brake supporting arm, one end of which is pivotally fastened to one of the said cantilever members so that it will extend beneath the end of said mandrel shaft seated in said mounting slots;

a precision'controllable magnetic brake secured on the free end of said brake supporting arm, and having a spur pulley on its rotatable brake member approximately aligned with said spur pulley on said quill shaft;

and a spur belt positively connecting the spur pulley on said quill shaft to the spur pulley on said brake rotor.

Jacobson Sept. 1, 1959 Bushnell et al Dec. 15, 1959 

2. IN A TORQUE GENERATING UNIT THE COMBINATION COMPRISING: A PAIR OF SPACED CANTILEVER MEMBERS, EACH HAVING A SHAFT MOUNTING SLOT EXTENDING HORIZONTALLY THROUGH ITS END; A MANDREL SHAFT, THE ENDS OF WHICH ARE SEATED IN SAID SHAFT MOUNTING SLOTS; A QUILL SHAFT BEARING-MOUNTED TO BE FREELY ROTATABLE AROUND SAID MANDREL SHAFT, AXIALLY ADJUSTABLE ON SAID MANDREL SHAFT, ADAPTED TO RECEIVE A ROLL OF FLEXIBLE WEB MATERIAL, AND HAVING A SPUR PULLEY FASTENED ON ONE END; 